A known implant for bone fixation in the related art has a bioabsorbable base material composed of pure magnesium or a magnesium alloy (for example, see Patent Literatures 1 and 2). Since magnesium decomposes by readily reacting with water, the outer surface of the implant is provided with an anodized membrane for the purpose of controlling the biodegradation rate of the implant after being implanted.